Field
The present invention relates to a fuel cell system.
Related Art
Various valves are used in a fuel cell system. Any of these valves may be frozen in a closed state during a stop of the fuel cell system. It is difficult to open the valve in the frozen state. This is likely to interfere with starting the fuel cell system. JP 2005-285686A discloses a technique of repeating opening and closing operations of a solenoid valve to eliminate the frozen state of the valve.
The target of this prior art technique is the solenoid valve that generates a relatively large force by the valve-opening and valve-closing operations. The valve-opening and valve-closing operations are thus expected to eliminate the frozen state to a certain degree. In the case of a motor-operated valve that is controlled to be opened and closed by a stepping motor, on the other hand, the simple valve-opening and valve-closing operations are unlikely to eliminate the frozen state. This is because the torque generated by the stepping motor is relatively small. By taking into account this problem, an object of the invention is thus to increase the likelihood that a motor-operated valve that is frozen in a closed state is opened by a stepping motor.